This valve works by the angular displacement of the anode rod causing a
change in distance between the grid and anode, with the resultant change in anode current. The part of
the anode shaft inside the valve body has a minimum free cantilever resonance of 12kHz, and thus the
valve can measure vibration up to that figure.

Heater voltage

6.3V

Heater current

150mA

Max anode voltage

300V

Max anode current

5mA

Max anode dissipation

400mW

Max heater cathode voltage

±90V

Typical conditions

Amplification factor (1)

20

Anode resistance (1)

72k ohms

Transconductance (1)

275 micromhos

Anode current (1)

1.5mA

Load resistance

75k ohms

Deflection sensitivity (2)

40V/degree; 2300V/radian

Moment of intertia of anode (3)

3.4 milligram/cm2

Rotational compliance of diaphragm (3)

0.0013x10-3 radian/dyne cm; 0.075 degree/gram cm

For anode shaft in undeflected position

Average change in voltage across 75k ohm anode load resistor when the anode shaft is deflected
from -0.5 to +0.5 degree. The plane of deflection of the anode shaft must coincide with the plane
through terminal no.5 and the axis of the valve.

Based on external anode-shaft length of 1/8" and the centre of the diaphragm as pivot.